Small molecule-based drugs continue to provide the foundation for developing therapeutic strategies for treating of most human illnesses. A substantial portion of drug development efforts within medicinal chemistry is, therefore, devoted to the synthesis of compounds for screening as drug candidates. Whether drug development efforts are directed toward specific bioactive targets or the synthesis of a library of selected derivatives, success in these endeavors is critically dependent on concurrent developments in organic synthesis methodology that allows the efficient and economical preparation of the targeted materials. Recognizing the synergism existing between chemistry and industrial drug development, this proposal details the development of new organic reaction methodology designed to access biologically active organic compounds efficiently and economically. Toward this goal, we will develop the reaction technology necessary to realize a general strategy for the catalytic synthesis of polypropionate-derived natural products. The composition of polyketides as repeating acetic or propionic acid units makes a modular synthesis strategy exploiting iterative installation of homologous monomer units an attractive synthesis strategy. Thus, we will develop a modular strategy for the catalytic asymmetric construction of stereochemically diverse polypropionate networks. The relevance of these reaction development activities to medicinal research and human health issues is exemplified in a de novo enantioselective total synthesis of the highly selective apoptosis regulator apoptolidin C. Heterocyclic small molecules are among the most ubiquitous features of new drug hits, important lead compounds, and commercially available pharmaceuticals. The development of a novel family of [4+2] and [2+2] cycloadditions for the asymmetric synthesis of highly substituted piperidine and [unreadable]-lactam derivatives, respectively, is inspired by the central role heterocycles play in pharmaceutical drug development efforts. Furthermore, efforts to develop catalytic asymmetric variants of these cycloadditions are intended to maximize the utility of these reactions in industrial medicinal and process chemical research.